1. Technical Field
The present disclosure relates generally to method for manufacturing printed circuit boards (PCBs), and particularly, to a method for forming electrical traces on a printed circuit board substrate using printing technology.
2. Description of Related Art
New ink jet circuit printing is an exciting new technology for creating the ultra-tiny microcircuits of PCBs that enable computers and personal electronic devices to get smaller and smaller each year. In a typical ink jet circuit printing method, an ink is printed onto a specified area of an insulated substrate, for example, a polyethylene terephthalate (PET) layer, using an ink jet printer, and thereby an ink pattern is formed on the insulated substrate. The ink contains silver nano-particles and solvents that keep the particles in a colloidal suspension. Then the ink pattern is sintered to remove the solvents, by a heating process at 200 to 300 degrees Celsius (° C.). After the solvents are removed, electrical traces are formed in the specified area of the insulated substrate. However, in the typical ink jet circuit printing method, the silver nano-particles in the electrical traces have loose contact with each other, and accordingly, the electrical traces has poor electrical conductivity. In addition, commonly used insulated substrates for PCBs are comprised of polymer such as PET, which has low heat resistance. Thus, even at 200 to 300° C., the insulated substrate may starts to soften and possibly deform, and the quality of the insulated substrate and the electrical traces may be compromised.
What is needed, therefore, is a method for forming electrical traces on a substrate which can overcome the aforementioned problems.